With the BloxOne DDI application, you can configure DHCP properties at the global level. You can also configure properties to the DHCP configuration profile. Properties can also be assigned to IP space, DHCP host, address block, subnet, address range, and fixed address levels. The DHCP properties follow a top-down inheritance hierarchy in which child objects automatically inherit DHCP properties from their parent objects. Thus, global DHCP properties remain at the top of the hierarchy and are inheritable to all child objects unless you override them at the object level.
For example, when you set DHCP properties for a particular DHCP server, these properties override the Global DHCP settings and apply to all objects served by that DHCP server. Properties set at the DHCP Server level override global settings and apply to the objects that reside beneath the DHCP server level. Properties set at the network level override object-level settings and apply to the objects within the network. Properties set for a DHCP range override those properties set at higher levels. For information about global DHCP properties, see Configuring Global DHCP Properties.
When a DHCP object contains inherited values from the parent objects, Cloud Services Portal displays the corresponding information when you create or modify the object. Based on the information, you can decide whether to override or keep the inherited values. You must have read/write permissions to the DHCP resources to override inherited values. You can only view inherited values and paths if you have read-only permissions.
This section includes the following topics:
Inheritance Hierarchy
The DHCP inheritance chain is based on a parent-child relationship where all objects above an object are considered parent objects to that object. All objects below the object are considered child objects to the object. A child object inherits the properties of its parent objects. When an object’s inheritance is overridden, the default, global hierarchical chain is broken, and properties may be assigned directly to the object at the object level.
In BloxOne DDI, a network (Address Block/Subnet) is associated with a DHCP Host. The DHCP Host might or might not possess any DHCP configuration. In addition, the DHCP Host can be associated with a DHCP Configuration Profile that contains DHCP configuration.
When evaluating the inheritance chain for Address Block/Subnet, BloxOne DDI considers the following scenarios:
(1) In the context of a given DHCP Host. In this example, the inheritance chain is Global DHCP Configuration > DHCP Config Profile > Subnet. The DHCP Config File is associated with the DHCP Host. The DHCP Host is used to identify which DHCP Server to use. In this scenario, the child objects inherit from the parent objects hierarchically above them.
(2) Outside the context of a given DHCP Host. In this case, the inheritance chain is: Global DHCP Configuration > IP Space > Address Block > Subnet. In this scenario, since a DHCP Host has not been configured, all child objects, in this example, the Subnet inherits from the DHCP Conf Profile.